Short Answer

If you start the day fasting in Ramadan and later break it by eating, drinking, or having intercourse, you must make up one day of fasting and offer a penalty [kaffārah] by fasting for two months straight. However, if you smoked, ejaculated during intimacy, or masturbated, this would break your fast, require one makeup day, but would not require a penalty because they are not entirely like eating, drinking, or intercourse.

Version 0.25

Shaykh Mustafa Umar